JPH0642811Y2 - Contact detection device between cutter blade and die in plastic granulator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a contact detection device between a cutter blade and a die in a plastic granulation device, and particularly to improve reliability of the contact detection device. Regarding new improvements.

[Prior Art] Japanese Patent Publication No. 56-46966, which is the applicant of the present application, describes a method of adjusting the degree of contact between a cutter blade and a die in a plastic granulator. In adjusting the degree of contact between the cutter blade and the die, it is very important to detect the contact between the cutter blade and the die.

FIG. 1 shows an example of a plastic granulating apparatus which carries out the method of adjusting the contact degree between the cutter blade and the die described in the above publication. When the parts related to the present application are explained, 1 is a synthetic resin. It shows a number of cutter blades rotating to cut molten string-like synthetic resin extruded through a nozzle 16 of an extruder die 3. The synthetic resin cut by the cutter blade 1 is thrown into the flow of pellet transport water that flows in the direction of the arrow through the underwater cutter box 24 of the granulating apparatus, is cooled by this water, and solidifies as pellets. The cutter blade 1 is fixed on the surface of the cutter holder 6 arranged toward the surface of the die 3 by an appropriate method. The cutter holder 6 is axially slidably attached to a hole (not shown) in the cutter shaft 2, and is also inserted into the hole of the cutter shaft 2 and a hollow portion (not shown) of the cutter holder 6, and is also a compression spring (not shown). Is always elastically pressed in the direction of the die 3.

Furthermore, one or a large number of electrodes 4 are embedded on the same circumference as the nozzle 16 of the die 3, and the wiring from the electrodes 4 is shown connected to the signal converter 5. The electrode 4 is insulated from the die 3 by an insulating material 15 such as ceramic.

In the plastic granulator shown in FIG. 1, the signal converter 5 is provided with a die 3 so as to obtain a continuous electric signal only when the cutter blade 1 is in contact with the surface of the die 3.
A positive electrode potential is applied to the insulated electrode 4. When the cutter blade 1 comes into contact with the die 3 and at the same time comes into contact with the end face of at least one electrode 4, the electrode 4 is grounded to the ground and the potential of the positive electrode becomes a low level, and the signal converter 5 makes this low level. Detected, cutter blade 1 is die 3
Generates an electrical signal indicating that the surface of the object has been touched.

[Problems to be solved by the invention] However, as described above, granulation of plastic is often performed in water or while flowing water,
In such a granulating apparatus, when the metallic electrode 4 is set to the positive electrode potential, a current flows from the metal to surrounding water, a local battery is formed there, and the positive electrode 4 made of the metal. Is electrolyzed and worn, the tip end surface of the electrode 4 sinks from the surface of the die 3, and even if the cutter blade 1 and the die 3 come into contact with each other, the cutter blade 1 and the electrode 4 do not come into contact with each other, and the signal converter 5 Does not generate an electric signal, or conversely, electrode 4
In many cases, the insulation between the end surface of the die and the die 3 became defective due to welding or the like, and the signal converter 5 often constantly generated an electric signal.

In particular, in the adjustment method in the above publication, it is important to accurately detect the contact time point between the cutter blade 1 and the die 3. However, when the cutter blade 1 and the die 3 contact each other by electric contact, the cutter If the blade 1 and the electrode 4 do not come into contact with each other, the adjusting operation itself may malfunction, which is a problem.

The present invention has a drawback that in the granulation of plastics performed in water or while flowing water, the electrode 4 does not come into contact with the cutter blade 1 due to electric contact, and the electrode 4 and the die 3 are welded to each other. It is intended to solve the drawback of outputting an electric signal even when the cutter blade 1 and the die 3 are not in contact with each other due to poor insulation.

[Means for Solving the Problem] The contact device between the cutter blade and the die in the plastic granulator according to the present invention is composed of the die and the cutter blade arranged so as to rotate in front of the die while supplying water. A plastic granulating apparatus for granulating, when the cutter blade contacts the die, an electrode embedded in the die so that a current flows between the cutter blade and the die, In a device for detecting contact between a cutter blade and a die in a plastic granulating apparatus, which comprises a pulse generator that generates a change in the current flowing between the die and the electrode as a pulse signal as the cutter blade rotates, The electrode is set to the negative electrode.

More specifically, it is a configuration including a current limiting unit for limiting the current flowing between the die and the electrode via the cutter blade to a predetermined value or less.

[Operation] In the contact detection device between the cutter blade and the die in the plastic granulator according to the present invention, the current flows into the electrode set as the negative electrode through the surrounding water, and the current value flowing into the electrode is very small. Since the electrode is not touched and worn away, it prevents the malfunction that the pulse current is not generated and the contact is not detected even though the cutter blade and the die are in contact with each other. be able to.

[Embodiment] A preferred embodiment of a contact detecting device between a cutter blade and a die in a plastic granulating apparatus according to the present invention will be described below with reference to FIG. FIG. 2 shows the inside of the signal converter 5 of FIG. 1 shown in the conventional example, and includes the same number of contact detection devices C _{1 to} C _{n as the} number of electrodes 4 embedded in the die 3. Contact detectors C _{1 to} C _n are connected to terminals S ₁ to C _n , respectively.
It is connected to each corresponding electrode 4 via S _n . Although only the contact detection device C ₁ is shown in detail,
The other contact detection devices C _{2 to} C _n have the same circuit configuration. Since the plastic granulating apparatus has the same configuration as that of the conventional example shown in FIG. 1, the configuration shown in FIG. 1 is used as it is and its description is omitted here.

Each of the contact detection devices C _{1 to} C _n is provided with a transistor Tr as an amplifier and a pulse transformer PT as a pulse detection unit, and further emits light indicating whether or not the cutter blade 1 is in contact with the die 3. A diode LED and LED 'are provided. In addition, a variable resistor Vr is commonly connected to the bases of the transistors Tr in each of the contact detection devices C _{1 to} C _n . The role of the variable resistor Vr is to control the conduction state of the transistor Tr so as to limit the current flowing from the die 3 to the electrode 4 via the cutter blade 1. Therefore, the variable resistor Vr and the transistor Tr form a current limiting unit 50.

In the above configuration, the die 3 positive potential is supplied through a terminal SP, and because a negative potential is applied via the terminals S ₁ to S _n in each electrode 4, the electrode 4 is Densawa It will not be done.

On the contrary, in the above configuration, the dice 3 which is given a positive potential.
However, it may form a local battery with the surrounding water and may be touched. However, when the surface of the die 3 is electro-touched, the tip end surface of the electrode 4 is projected to the surface of the die 3, and the cutter blade 1 rotating on contact with the surface of the die 3 rotates. The protrusion of the tip surface of the electrode 4 having a small area ratio has almost no influence on the granulation operation, and in terms of contact detection, the tip surface of the electrode 4 is reliably projected from the surface of the die 3. Touch detection is performed.

When the cutter blade 1 and the electrode 4 come into contact with each other as the cutter blade 1 rotates, a minute current flows at the point A. Since this minute current changes depending on the quality of water used, it is limited by the variable resistor Vr and the transistor Tr so that the current value does not exceed a predetermined value manually or automatically. In this way, since the generated current is slightly suppressed by the variable resistor Vr and the transistor Tr, the die 3 to which a positive potential is applied is supplied.
The possibility of being touched or the speed of touch is reduced.
The minute current generated at the point A is amplified by the transistor Tr and supplied to the pulse transformer PT.

Since this pulse transformer PT transmits only the pulse signal, it transmits only the pulse current to the point C regardless of the continuous current at the point B.

When the cutter blade 1 is not in contact with the electrode 4 as the cutter blade 1 rotates, the points A and B are continuously connected depending on the insulation resistance of the electrode 4 or the conductivity of the water in which the electrode 4 is immersed. Current flows, but is not transmitted to point C.

When the cutter blade 1 is in contact with the electrode 4 due to the rotation of the cutter blade 1, a current pulse due to a short circuit of the cutter blade 1 flows to the points A and B in addition to the above continuous current. . Only this current pulse is transmitted to the point C by the pulse transformer PT. The generated pulse is taken out as an output signal to the point D through a delay circuit etc.
Activates or flashes the LED. When any one of the plurality of light emitting diodes LED is energized, the light emitting diode LED 'commonly connected to the light emitting diodes is also energized accordingly.

If the cutter blade 1 and the electrode 4 do not come into contact with each other, only the above-mentioned continuous current flows to the points A and B, so that the point C
Is not pulsed and therefore the light emitting diode
The LED never flashes.

Further, when the insulation between the electrode 4 and the die 3 becomes defective due to electric contact or other factors, a continuous current flows in the points A and B and does not change, so that a pulse is not applied to the point C. There is no output and therefore the light emitting diode does not flash.

As described above, according to the present invention, it can be seen that the light emitting diode is activated only when the cutter blade 1 and the die 3 are in true contact to notify the fact.

[Advantages of the Invention] As described above, according to the present invention, by keeping the electrode at a negative potential, the electrode is prevented from being electro-touched and worn, and the cutter blade and the die are in contact with each other. Despite this, no pulse current was generated, and the malfunction of not detecting contact disappeared.

Further, by limiting the value of the current flowing between the die and the electrode to a very small amount, it is possible to reduce the possibility that the die will contact with electricity or the speed of contact.

Further, since the light emitting diode is not energized even if a current flows constantly due to poor insulation caused by deterioration of water quality or metal welding between the electrode 4 and the cutter blade 1, the cutter blade 1
Therefore, there is no erroneous recognition that the die 3 is in contact with the die 3, and therefore there is an effect that the risk of malfunction is eliminated when the method for adjusting the degree of contact between the cutter blade 1 and the die 3 in the above publication is carried out.

[Brief description of drawings]

FIG. 1 is a sectional view showing a conventional plastic granulating apparatus to which the present invention is applied, and FIG. 2 is a circuit diagram showing a contact detecting device according to the present invention. In the figure, 1 is a cutter blade, 2
Is a cutter axis, 3 is a die, 4 is an electrode, 5 is a signal converter,
C _{1 to} C _n are contact detection devices, LEDs and LED 'are light emitting diodes, Tr is a transistor, PT is a pulse transformer (pulse generator), Vr is a variable resistor, and 50 is a current limiting unit.

Front page continued (72) Inventor Yuji Kamigaki, 6-1, Funakoshi-minami, Aki-ku, Hiroshima City, Hiroshima Prefecture Japan Steel Works, Ltd. (72) Inventor Shigeyoshi Kinomoto 1-6, Funakoshi-minami, Aki-ku, Hiroshima-shi, Hiroshima No. 1 inside Japan Steel Works, Ltd.

Claims (2)

[Scope of utility model registration request] 1. A plastic granulating apparatus comprising a die (3) and a cutter blade (1) arranged so as to rotate in front of the die for granulating while supplying water. When (1) contacts the die (3), an electrode (4) embedded in the die (3) so that a current flows between the die (3) and the cutter blade (1). And a pulse generator (PT) for generating a change in current flowing between the die (3) and the electrode (4) as a pulse signal as the cutter blade (1) rotates, A device for detecting contact between a cutter blade and a die in an apparatus, wherein the electrode (4) has a configuration set to a negative electrode, the device for detecting contact between a cutter blade and a die in a plastic granulating device. 2. A current limiting section (50) for limiting a current flowing between the die (3) and the electrode (4) through the cutter blade (1) to a predetermined value or less. A contact detection device between a cutter blade and a die in a plastic granulation device according to claim 1, wherein the device is a utility model registration device.